The present disclosure relates generally to a glenoid component for a use in a shoulder arthroplasty, and an associated method of implanting the glenoid component in a scapula of a patient.
It has become common to perform a shoulder arthroplasty to repair a patient's shoulder joint which has become dysfunctional due to disease or trauma. During such a procedure, the natural glenoid surface of the scapula is resurfaced or otherwise replaced with a prosthetic glenoid component which provides a bearing surface for a head of the humerus or a head portion of a humeral prosthesis (hereinafter “humeral head”).
Various glenoid components have heretofore been designed to include a base component that defines a bearing surface on a humeral-facing side and a number of pegs that extend from a scapula-facing side of the base component. These pegs may include relatively long anchor pegs having a plurality of radially extending fins and/or relatively short stabilizing or anti-rotation pegs which may or may not have a series of grooves defined therein. One example of an existing glenoid component possessing the above-described configuration is disclosed in U.S. Pat. No. 6,911,047, the disclosure which is herein incorporated by reference in its entirety.
The pegs of this type of existing glenoid component extend from the scapula-facing side of the base component so that the axes defined by the pegs are parallel with respect to each other. One drawback of glenoid components with parallel oriented pegs is the inability in some instances to reach healthy bone stock remaining in a patient's scapula. In particular, there are many clinical situations in which a patient's scapula possesses deficient bone stock at the locations which align with the relatively long, parallel anchor pegs. Thus, upon implantation of the glenoid component, the anchor pegs reside in deficient bone stock thereby causing an unstable attachment of the glenoid component to the patient's scapula. Interestingly, in many of these clinical situations, healthy bone stock is observed in other locations of the glenoid region of the scapula.
In order to address this problem, some existing glenoid components possess pegs extending from the scapula-facing side of the base component which are divergent with respect to each other. Being configured divergent, the pegs are targeted to be embedded in healthier scapula bone stock for more effective anchoring of the pegs. One example of this type of glenoid component is disclosed in U.S. Pat. No. 5,593,448 (hereinafter “the '448 patent”).
However, providing the pegs of the glenoid component with a non-parallel orientation (e.g. divergent or convergent) causes some challenges for implantation of the device. Significantly, during implantation, the pegs of the glenoid component do not physically align with the bores drilled in the scapula for receiving the pegs. In contrast, pegs having a parallel orientation with respect to each other align with drilled bores thereby facilitating implantation of the glenoid component. In order to address the implantation challenge of non-parallel peg type glenoid components, the '448 patent teaches that its base component is configured to flex or deform so as to cause its pegs to become temporarily more aligned with the holes defined in the scapula so that insertion of the pegs therein is enabled.
There are drawbacks associated with providing a glenoid component having a readily flexible or deformable base component. Indeed, the base component of a glenoid component, when implanted, receives a significant amount of force during normal use. In particular, the humeral head articulates against the base component of the glenoid component during normal human use. If the base component flexes or deforms when the humeral head is urged against it, unnatural forces may be applied to the soft tissue and muscles that interconnect the humerus to the scapula. These unnatural forces may cause damage to such soft tissue and muscles. In addition, pain or discomfort to a person in which the glenoid component is implanted may result due to the unnatural forces.
Additionally, creating a base component of a glenoid component from materials that are more flexible or deformable may result in a base component which is less durable in relation to non-flexible or non-deformable base components (i.e. conventional base components). Thus, during normal use of the shoulder joint, articulation of the humeral head against the flexible or deformable base component may cause relatively rapid deterioration of the base component thereby resulting in early failure of the glenoid component. Moreover, wear debris may be more readily generated in such a device.
What is needed therefore is an improved glenoid component that possesses non-parallel oriented pegs (e.g. diverging or converging pegs). What is also needed is an improved method of implanting such a glenoid component in the scapula of a patient. What is further needed is a glenoid component with non-parallel oriented pegs that has a base component which possesses the degree of structural integrity equivalent with base components of conventional glenoid components. What is additionally needed is a glenoid component having non parallel oriented pegs that has a base component that does not flex or deform significantly during articulation of a humeral head there-against. What is also need is a glenoid component having non parallel oriented pegs that do not generate significant wear debris during articulation of a humeral head there-against. What is further needed is a glenoid component having non parallel oriented pegs that do not cause unnatural forces to be applied to the soft tissue and muscles that interconnect the humerus to the scapula during articulation of the humeral head against the base component of the glenoid component. What is further needed is a glenoid component having non parallel oriented pegs that do not cause damage to such soft tissue and muscles that interconnect the humerus to the scapula during articulation of the humeral head against the base component of the glenoid component. What is also needed is a glenoid component having non parallel oriented pegs that does not cause pain or discomfort to a patient in which the glenoid component is implanted during articulation of the humeral head against the base component of the glenoid component. Additional features and advantages of the present disclosure will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiments.